LIGHT-TRANSMITTING ALUMINA TUBE

PURPOSE:To provide an alumina tube having an excellent transmittance by mixing alumina powder with water, a deflocculating agent and a magnesium compound to make a slip which is then subjected to casting before sintering. CONSTITUTION:0.5 Parts of polyacrylamide used as a deflocculating agent is added to mixture consisting of 100 parts alumina powder, 18 parts purified water and 0.3 parts magnesium phosphate. Following that, the thus prepared slip material is formed into a ceramic tube 10 for an emission tube as shown in the figure by a mud-exhausting casting method using a gypsum mold. The thus obtained molded body is provisionally sintered at 900 deg.C for two hours before being sintered in an atmosphere of hydrogen at 1,800 deg.C for 10hr, thereby obtaining a light-transmitting alumina porcelain. By chemically polishing the inner and the outer surfaces of the tube, irregular reflection of beams sent from a light source installed inside the tube is decreased and the rate of light transmitted outside the tube is increased.